Stroke control for free-piston units



Aug. 2e,"1947.

A. KALIITINSKY 1196. July 23, 1943 INVENTO M ATTORNEY Aug. 26, 1947- A. KALITINSKY STROKE CONTROL FOR FREE-PISTON UNITS Filed July 23, 1943 2 Sheets-Sheet 2 Y INVENTOR mm 'ATTORNEY Patented Aug. 26, 1947 UNITED STATES PATENTQFFICE A Andrew Kalitinsky, Eagleville, Conn, assignor to United Aircraft Corporation, East Hartford,

Conn.;.a corporation of Delaware Application July 23, 1943, Serial No. 495,91s

2 Claims. (01.230-56) This invention relates to a free-piston 'enginepressedalr leaves the cylinders through discharge and-compressor unit adapted for compressing valves 42, also at opposite ends of the compresgas'eous media of various densities. sor cylinders, and passes through scavenge mani- In a conventional free-piston engine-and-comfold it through ports l6 and 48 which are unpressor unit, the compressor, when designed for covered by pistons" and H at the end of the compressing one density of medium, is improperpower stroke, thereby permitting airto be blown ly dimensioned for compressing other densities. through the engine cylinder and exhaust ports An object of the invention is to overcome the 50 and52 into exhaust manifold 54. above difllculty so that the unit will operate prop- The engine-and-compressor unit operates to erly regardless of density. 10 best advantage provided the density of the me- Free-piston engines are usually of the two-cycle dium being pumped by the compressor remains type and exhaust ports which are near the ends uniform. Achangein the density of the medium of the engine cylinder must be fully uncovered being pumped shortens or lengthens the piston by the pistons for proper engine operation. A stroke so that, either the engine ports are not variation in the density of the medium pumped I fully uncovered or, in the case of an excessively by the compressor affects the length and posilong stroke, the pistons may strike each other or tion of the piston stroke and may cause incomthe ends of the cylinders. When the unit is used plete uncovering of the ports. One feature of in aircraft, the change in the density of the methe invention is the avoiding of this difficulty by dium between sea level and cruising altitude is controlling the flow of the medium through the enough so that adjustments are necessary for efcompressor cylinders. flcient operation of the unit. In this invention When these units .are used in aircraft, if they the length of the piston stroke is adjusted by are designed for-one ambient pressure, i. e. alticontrollingthe flow of the medium through the tude, they are not. properly designed for other compressor cylinders. v altitudes; Another feature of the invention is If the density increases substantially above the control of a free-piston unit so that its opthat for which the unit is designed, the strokes eration may be independent of altitude changes. of the pistons shorten to such an extent that the Other objects and advantages will be apparscavenging and exhaust ports oi-the engine cylent from the specification and claims, and from inder are not fully uncovered during th piston the accompanying drawings which illustrate an movement. To adjust for this increase in densiembodiment of the invention. ty, interconnected valves 56 and 56 are provided Fig.1 is a sectional view through the free-pisin the passages 58 leading from intake manifold ton engine-and-compressor unit. 38 to the chamber "60 whlch'communicates with Fig. 2 is a fragmentary section taken on line intake valves 40 at the inner ends of the compres- 22 of Fig. 1. sor cylinders. In effect, throttling by closing The unit shown includes an engine cylinder valves 56 and 56 tends to convert the unit into I0 having reciprocating pistons l2 and M to which a single-acting compressor with the work of com compressor pistons l6 and iii in cylinders 20 and pressing being done in the outer ends of the com- 22 are integrally connected. Sleeves 24 and 26 pressor cylinders. attached to the compressor pistons complete the Since substantially all the energy developed in reciprocating piston assemblies. The sleeves in the engine cylinder must be absorbed during the combination with stationary pistons 28 and 30 outer stroke of the pistons, the stroke will be form air spring cylinders. lengthened and the engine ports will be fully The piston assemblies are moved apart by the uncovered. The unit is thus adapted to compress burning of fuel injected into engine cylinder i0. a medium of greater density, Without afiecting Air compressed in the air spring cylinders on the the operation of the unit, by clos a es 56. power stroke returns the piston assemblies. The These may be Op t d y a d 5? On w i h assemblies are maintained at equal distances from valves 56 are mounted and a parallel rod 62' onthe center of the engine cylinder by a linkage which valves 56' are mounted. A linkage 63 conwhich may include racks 34 extending from the nects the rods 62 and 62 so that the move sicompressor pistons and engaging opposite sides multaneously when rod 62 is turned. Rod 82 may of a pinion, not shown. have an arm 64 by which the Valves may be man- Intake manifold 38 conducts air to intake valves ually controlled. 40 through which air alternately enters opposite It is to be understood that the invention is not ends of the compressor cylinders. The comlimited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

1. A free-piston engine-and-compressor unit including an engine cylinder having scavenge and exhaust ports, a compressor cylinder having intake and discharge valves at each end, free pistons in said cylinders and reciprocating as a unit, said pistons having a variable length of stroke with the piston in the engine cylinder adapted to cover and uncover said ports, a supporting structure interconnecting said engine and compressor cylinders and forming a passag for the admission of gas to the end of the compressor cylinder adjacent to the engine cylinder, in combination with means for throttling the admission of gas to the end of the compressor cylinder adjacent the engine cylinder.

2. A double acting free-piston engine-andcompressor unit including an engine cylinder having scavenge and exhaust ports, a compresso cylinder adjacent each end of the engine cylinder, each compressor cylinder having intake and discharge valves at each end, a supporting structure interconnecting the compressor and engine cylinders and forming passages therein communicating with the inlet valves at theinner ends of the compressor, engine pistons in said engine cylinder and compressor pistons in the compressor cylinders, each compressor piston being connected to and moving with the adjacent engine piston, each engine piston having a variable length stroke and being adapted to cover and uncover the ports and means for limiting the admission of gas to the inner ends of the compressor cylinders including throttles located in the passages to the inner ends of the cylinders and means for moving all of the throttles simultaneously.

ANDREW KALITINSKY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS 7 Date Number Name 2,295,728 Gess Sept. 15, 1942 1,649,298 Halleck Nov. 15, 1927 1,969,076 Hirsch Aug. 7, 1934 2,137,752 Ferguson Nov. 22, 1938 2,170,358 Wainwright Aug. 22, 1939 1,612,933 Metzgar Jan. 4, 1927 669,140 Knapp Mar. 5, 1901 849,916 McKeen Apr. 9, 1907 2,090,424 Pescara Aug. 17, 1937 2,038,442 Pescara Apr. 21, 1936 2,090,709 Steiner Aug. 24, 1937 Steiner Feb. 21, 1939 

